In recent years, following an increase in the degree of density and integration of hybrid ICs and printed circuit boards carrying transistors, ICs, memory elements, and other electronic components, various heat conductive silicone compositions have been used to provide high-efficiency heat dissipation for them. Heat conductive silicone greases, heat conductive silicone gel compositions, and heat conductive silicone rubber compositions are known as such heat conductive silicone compositions.
Examples of such heat conductive silicone compositions include heat conductive silicone compositions utilizing a silicone oil as the primary ingredient and containing inorganic fillers such as zinc oxides and alumina powders (see Japanese Unexamined Patent Application Publication No. Sho 50-105573, Japanese Unexamined Patent Application Publication No. Sho 51-55870, and Japanese Unexamined Patent Application Publication No. Sho 61-157587), heat conductive silicone compositions comprising organopolysiloxanes, organopolysiloxanes having acyloxy groups or alkoxy groups attached to silicon atoms, heat conductive fillers, and curing agents (Japanese Unexamined Patent Application Publication No. 2000-256558), and heat conductive silicone compositions containing organopolysiloxanes, curing agents, and heat conductive fillers surface-treated with silalkylene oligosiloxanes with silicon-bonded alkoxy groups (Japanese Unexamined Patent Application Publication No. 2001-139815).
The problem with such heat conductive silicone compositions, however, is that attempts to increase the amount of fillers in the compositions causes the viscosity of the resultant compositions to rapidly rise and their handling properties drastically deteriorate.
It is an object of the present invention to provide a heat conductive silicone composition possessing excellent handling properties despite containing a large amount of heat conductive filler.